Process of cinematography in natural colors



L. MAUCLAIRE.

PROCESS OF CINEMATOGBAPHX IN NATURAL COLORS. APPLICATION man {EB.9,1918.

1,421,279. Patented June 27, 1922.

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OH DU 6 I unuunn UNITED STA S LQUIS maucmmn, or rams, raancn, ASSIGNOR TO HIMSELF, ANDRE samsamm,

PATENT orncs.

AND GEORGES GAUTIEB, OF PARIS, FRANCE.

PROCESS OF CIN EMATOGRA PHY IN NATURAL COLORS.

Specification of Letters Patent. hPaten'ted J ne 27-, 1 2

Application filed February 9, 1918. Serial No. 218,427.

(GRANTED annex mm rnovrsrons or THE ACT or MARCH 3, 1921, 41 srar. L, 1318.

To all whom it away co'ncemif Be it known that I, LOUIS MAUCLAIRE, a citizen of the Republic of France, residing in Paris, France, have invented certain new and useful Improvements in Processes of Cinematography in Natural Colors (for which I filed application in France, July 23, 1917, Patent No. 487,501), of whichthe following is a specification.

This invention relates to the art of cinematography in natural colors and has for its object to" provide a process of cinematography in colors which enables, a perfect projection to be obtained from the point of view of fixity, accuracy of the colors, and of facility of manipulation of the apparatus, without any additional expenditure of light.

It is known that cinematography innatural colors is based upon the employment of monochrome (single-color) views, for instance, two, three, four or more selected views, through screens, the sum of which gives white; by superposing these views the view with all its colors is obtained. Theoretically and practically bichrome (twocolor) decomposition is insufiicient and the selection in order to give exact results should be at least trichrome (three-color). A tetrachrome (four-color) selection gives good results but causes an undue complication of the apparatus.

In the processes employed heretobefore a certain numberv of monochrome views are taken either successively or simultaneously, and are successively or simultaneously projected; or, the views may be taken simultaneously, and projected successively, or I vice versa.

Inorder to obtain perfect results it is of the first importance that the number of views which are to be superposed should be taken simultaneously. All the processes heretofore known, except that constitutingthe present invention may without exception be divided into the two following classes.

(1) Those in which each of'the two, three or more monochromes is projected succes-' gsive'ly.

vantages; in fact when the monochromes are projected successively the eye of the spectator has to effect their synthesis by employng thepersistence of the images upon the retina which naturally causes the spectators great fatlgue. Further, if ima es of the normal size are taken correspon ing to the unages of cinematography in black the strip Will be two, "three or four times longer and will pass in front of the object glass at a speed two, three or four times as great according as the selection is a two, three or four-colored one, a fact which entails the rapid wear of the apparatus and frequent breakages of the film, thus necessarily increasing considerably the expense involved in these processes.

The processes comprised in the second class are better than the first mentioned but nevertheless they have very serious defects.

The fact isthat in order to have perfect colors it is necessary to project simultaneously at least three monochromes, which may be done under one or the other of the two following sets of conditions:

(1) The three, four or more monochromes may cover the surface of one normal image of cinematography in black; they will thus be very small and will have to undergo a very considerable enlargement; further, the special apparatus necessary requires very complicated object glasses.

(2) Each of the three, four or more monochromes may have dimensions equal or approximately equal to the images in black, thus requiring a very considerable length of strip, excessive speed of unrolling, frequent breakages of the film, and the necessity for a much more powerful light, since it is necessary to illuminate a greater surface of ima es.

The separation between the axes of the object glasses corresponding to the extreme monochromes becomes very great and owing to thisfact the ima es are no longer alike and therefore can no onger be exactly superposed; this fact explains the presence of colored fringes.

- The selection is of aspecial kind in that .it is trichrome but is devel '1 ped upon four *ranged in a manner to automatically balance far as their dimensions and their'distribution upon the film are concerned;

(3) An obturator of the. camera is arthe monochrome negatives;

(4) A rotary screen-carrier for the pro-, j'ection;"

(5) The construction of the projecting object glasses.

Figures 1 and 2 are diagrammatic views, illustrating in connection with the description, certain principles based upon the Chevreul chromatic circle;

Figs. 3, 4 and 5 indicate novel forms of. films.

Fig. ,6 illustrates a novel form of obturator.

Figs. 7 and 8 are diagrams illustrating the arrangement and adjustability of the objective lenses.

Fig. 9 is a view similar to Fig. 7, showing the objectives arranged for an arrangement of color records upon the film different from the arrangement of the records on afilm for use with the objectives of Fig. 7.

Fig. 10 is a view illustrating a novel color screen.

Fi s. 11 and 12 illustrate a construction of co orscreen in which the intensity and tone are varied in the direction of the line of travel of the'screen.

In order to describe the selection as clearly and precisely as possible the chromatic circle called the 'Chevreul circle will be employed, that is to say, the solar spectrum is distributed in a circular'form, the colors becoming fainter towards the centre which is white.

Referring to 'Fig. 1 of the accompanying drawing, this circle has the properties, firstly, that a color indicated at M is exactly complementary to the color M diametrically opposite and secondly, that a po nt P compounded with the colors M and N will contain these colors mixed in the ratio of the segments M P and P N.

The best selection being the trichroine is that adopted for the improved process, but in order to render it more practical it is obtained in the following manner. Referring to Fig. 2, the two colors A, B of the trichrome selection are preserved intact, but

the third color 0" is decomposed. into two elementary tints A and B, located onthe prolongations of the linesv A0 and B0. In,

[this manner four monochromes are obtained corresponding to-a trichrome selection. Re

- capitulating this phenomenon, it is to be noted that the colors A ,.B ,C are located at the three angles of an equilateral triangle within the Chevreul circle; that two points are preserved as they are without any modification (for instance the points A B while the third point is decomposed into two elemetary colors A B, such that A is located on the straight line AQ produced and B on the straight line BO produced.

The angle AOB may be varied, but in order to employ the screens to the best possiible advantage and to obtain the ma-xlmum exactness in the reproduction of the colors, the angle AOB should be made equal to 120 degrees.

This selection (if the points A and B on the circle are considered) is tantamount to a double bichrome, A being complementary to A and B complementary to B but each of the groups A A and B B is connected to the other by reason of the fact that the points A and B are at two angles of an equilateral triangle inscribed in the Chevreul circle, the triangle having any desired position within the said circle.

The view .projected with all its colors will thus comprise four images corresponding to the colors of selection A A 13 B and these images will be distributed in two groups of which the first group comprises the images obtained with the screens A and A and the second group comprises the images obtained-with the screens B and B, each group including images such that their superposition upon the screen will give a View in natural colors in nearly all the colors and tones. 1

The superposition of thetwo groups will give the tints rigorously exact with all their intensity and their varieties and the eye of simultaneously and which constitute one group are taken simultaneously, and each such group will given on projection a view in vivid natural-colors and rich in a variety of tints, the superposition of the two groups only having the effect of perfecting the colors in all their delicacy and giving a result which is theoretically and practically perfect. It is to be noted that the screens used. for the projection differ from those employed in taking the view by reason of taking into account the difference in composition between solar light and the light employed for the projection.

As regards the dimensions of the images 126 and their distribution upon the film, two

different arrangements may be made use of these two cases will now be described. 130

horizontally longitudinally of itself. Each of these images 18 12x18 millimeters and it will be seen that in this case the usual cinematographic size and form is preserved.

For the second case in which the feed pini ions of the film are modified a special perforation is adopted; in this case further advantages are obtained by reason of the fact that the apparatus preserves its normal. position, the film unrolling in the ordinary direction whereas in the preceding case the film has to unroll horizontally; but the special perforation indicated in Figs. 4: and 5 is employed. The images 1, 2, 3, i are disposed in the usual manner and their dimensions are 12x16 mm, the images in each group being separated by a space of 1 min. The groups are separated from one another a sutficient distance to enable two, three or four holes to he made in the strip in order to easethe operation, as illustrated in Fi at which shows four such holes; similar ho es may also he made between the ima es of each group as shown in Fig. 5. This istributionof the images upon the film is of advantage because by maintaining a normal 7 speed of the film the number per second will be increased from ten to fifteen per cent, is

minish the sparking and will at the same time be of benefit to the spectators.

' In order to ohtainmonochromc negatives the luminous rays will be filtered by means pf thescreens explained alcove, that is to I say two normal screens of the triohrome selection and two other screens the sunset which givesthe third tint oi the trichroinc. The images 1 and 3 pass in front of one ohjefict lass and 2; and 4- in front of the other, t e glasses being equal to the distance between the geometrical centres of the images 1 and 2 or 3 and l.

A special taking obturator is necessary oecause the four screens for taking the views have not exactly the same timesof exposure, that is to say they ahsorh'more or less of the luminousrays owing to being more or less opaque. the images exactly But in order. to have snperposahle' in subscquent projection it is necessary that they should be identical, that is, they should have the same distinctness at difierent-planes and this implies the condition oi equal diapliragming the two object glasses In o'rpara place the images in equilibrium the "ohturator arrangement shown in Fig. 6 may be employed, which gives, when desired, four group are arranged as shown in Fig.

istanccof the axes or the two object.

differently timed exposures. The openings 1, 2, 3, {1, corresponding to the images 1, 2, 3, 4-, have a useful area proportional to the opacity of the screens for taking the views A, A, B B and also inversely proportional to the sensitiveness of the emulsion to the radiations corresponding to these screens.

It can be seen that the time of exposure for one uniform revolution of the axis of the obturator is Proportional to the angle at the centre corresponding to each of these openings. In the case shown in Fig. 6 the exposures are in the increasing order 3, 2, 1, 4, that is to say, the screens are in the order or increasing transparence to a .perfectly orthochromatic sensitization 3, 2, Lot,

which also corresponds to the respective senofthe monochrome negatives is e ected automatically thus enabling the two diaphragms of the object glasses 0 O to be connected'by a small rod and thus obtain images of identically the same distinctness whatever the depth of the field may be, the

images being thus exactly similar and com sequently easily su' erposable. Haying thus obtained the negative film a positiveprool [is prepared in (the same manner as for cinematogra' hy in lolack.

In or or that the positive film may be projected and exactly reproduced, the View y in colors should be placed under conditions reason of their form, a fact which will dlanalogous to those underwhich the view was taken, that is to say each group of inn toscreens correspon ing; to those used in taking the view. These projecting screens differ materially from those used in taking theview as the electric are used for projection has not the seine spectrum as solar light. Thus each group ofimages should he placed in front of the projecting object glasses at the same time as the correspond I i119: screens.

The projecting object glass and a screen carrier will now be described. The special object glass for projection in colors is compounded of two object glasses 0', 0 cut to the dimensions oi the images, their axes being the same distance apart as that, separating the geometrical centres of the two images of. a group. These two object glasses are placed in the same tuhe'and one ofthem is fixed whilethe other islinlred in a man- :ner 'enablingit to oscillate both in a horizontal and in a vertical direction asindi cated by thearrows on'Figs. 7 and 9 in orderthat the-two luminous bundles of rays may lee-caused to converge upon the screen and the two images he made to coincide exactly. The object glasses are disposed as lid shown in Figs. 7, -8 and 9, according as the stri s havenormal or special perforations.

igs. 7v and 8 show a section and a diagram illustrating the regulating arrange ment for films having normal perforations while'Fi 9 shows an arrangement for special per orations. The two object glasses I are arranged to be simultaneously focused,

' in any suitable manner. It will of course be understood that the two object glasses, as far as their optical composition, construction and focal distances are concerned, should be absolutely alike. The pro'ecting screens are disposed as shown 1n ig. 10 the screen carrier disc making one revolution for the rejection of two groups of monochromes, t at is to say, for one complete view or, also for two fi'hn shifts. If the film has the usual perforations it will be arranged as shown in Fig.

10, the screens 2 and 4 passing in front of the same object glass and the screens 1 and 3 passing in rout of the other object glass, while two opaque portions N N come- 1n front of the object glass during the filmshift. These portions N N may be omitted if the ordinary obturator of the projecting apparatus remains, this obturator rotating twice as fast as the screen carrier disc and consequently making one revolution per film-shift. 1

The projecting screens might .be either homogeneous or divided up as may be desired. If the latter they will be as shown in Figs. 11 and 12. Fig."11 shows a screen divided up from the centre C towards the two ends A and B while Fig. 12 shows a screen divided upfrom one end A towards I stituting each sector of. the screen carrier the other B. By the term divided up it is to be understood that the screens conscreens are stuck together by thin metallic parts arranged according to the radii of the screen carrier disc. The screen carrier may be constructed "of the lightest possiblematerials such as aluminium or pasteboard.

Claims:

1. A processof taking or projecting motion pictures in color, comprising taking or projecting an image or scene in sets of four color records, two of the records being of stantial ngth to be divided- 7 screens which inpractice. facilitates the construction, and the partial colored part of the screen having a varying color tone.

2. A process of taking or projecting motion pictures in color, comprising taking or projecting an image or scene in sets of four color records, two of the records being of primary colors, and two being records of two colors whose combination constitute the third primary color complemental to the colors of the two primary color records aforesaid, and interposing a moving colored screen having the transparency of the several arts of the screen varied to give subl y equal illumination. 3. A process of taking or projecting motion pictures in' color, comprising taking or projecting an image or scene in sets of four color records, two of.the records being of primary colors, and two being records of two colors whose combination constitute the third primary color complemental to the colors of the two primary color records aforesaid, and interposing a moving colored screen having the four colors selected, each colored part of the screen having a varying tone and the transparency of the several parts of the screen varied to give substantially equal illumination.

4. A process of cinemato aphy in colors,

comprising making a se ection of four images in groups of two, taken simultaneously, taken through selection screens, two of which are ofprimary colors, the two other screens being of colors obtained by the decomposition of the third rimary color complemental to the two otl ierprimary colors aforesaid, and obturating the views by an obturator having .four openings, each opening corresponding toa screen, and said open- .ings having an area proportional to the angle or center corresponding to each open ing, to the opacity o the screens, and inversely to the sensitiveness of the emulsion for radiations corresponding to the screen, and projecting the four. 1m "3 through four pro ection screens-mounte upona circular support, the, said projection screens differing .from the taking screens only by the difference of spectral. composition-between sunlight and the artificial light employed f or projection.

In w1tness whereof, I have hereunto signed my name in the scribing witnesses.

presence of two sub- LOUIS MAUCLAIRE.

Witnesses:

Cnas. P. Pmcssnr RENE BARDY. 

